In response to this RFA that requests innovative and developmentally- based intervention projects that stem from knowledge gained from studies of risk, etiology, and basic behavioral processes, this application, proposes to test a Family-based preventive intervention with two-year-old children at risk for developing significant conduct problems, providing the necessary pilot data to test the model's applied efficacy. The Investigative team's programs of research have identified specific parenting factors and family profiles that are associated with early onset and persistence of serious conduct problems from infancy to the school-age period that have yet to be tested as an intervention. Despite prior longitudinal research that has shown that early-starter children go onto show the most chronic and severe forms of antisocial behavior, a developmentally-based, ecologically sensitive intervention initiated during the toddler period has yet to be tested with extreme-risk families to examine if antisocial trajectories are preventable before the child's and family's behaviors are less malleable to change. This project will test the efficacy of Dishion's Family Check UP intervention package with a group of 120 extreme-risk families recruited from WIC sites in Pittsburgh, PA. As well as drawing on a well-established evidence base, the intervention will incorporate novel preventive strategies into the Family Check Up package from Shaw's and Gardner's developmentally based research. Extreme-risk status will be based on the presence of child, parent, and sociodemographic risk factors. It is expected that early intervention will be associated with improvement in parenting and child behavior, whereas families in the nonintervention group are likely to show decreases in parental functioning and growth in child conduct problems.